


An Alpha Always Knows

by TobytheWise



Category: Shadowhunters (TV)
Genre: Alec Lightwood in Heat, Alpha Magnus Bane, Bottom Alec, Established Relationship, Fanart, Fluff and Smut, M/M, Mating Bites, Mating Cycles/In Heat, Nesting, Omega Alec Lightwood, Plot What Plot/Porn Without Plot, Power Bottom Alec Lightwood, Rimming
Language: English
Status: Completed
Published: 2019-05-12
Updated: 2019-05-12
Packaged: 2020-03-02 05:13:50
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,434
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18804430
Author URL: https://archiveofourown.org/users/TobytheWise/pseuds/TobytheWise
Summary: After Jace texts Magnus, demanding his presence at the Institute to take care of his pre-heat omega, Magnus finds a shirtless, sweaty Alec attempting to take his frustrations out by sparring his parabatai. Luckily for Alec, Magnus is more than happy to help him relieve stress in another, more mutual beneficial way. What starts off as Magnus helping his omega, quickly merges into them exchanging mating bites.





	An Alpha Always Knows

**Author's Note:**

  * For [ratafia](https://archiveofourown.org/users/ratafia/gifts).



> This is just super self indulgent omegaverse smut as a reward for editing my novel haha. I hope y'all enjoy <3  
> Now with fanart from the lovely [lieselfh](https://lieselfh.tumblr.com/) <3 Thanks again for bringing these boys to life! You are AMAZING!!

Magnus walks through his closet, confusion no doubt written all over his face. He could have sworn he had a certain black shirt but no matter how long he looks for it, he just can’t find it. He tries to shrug it off, looking for a different shirt that’s similar but in a dark purple color, and can’t find that either. Magnus lets out a huff, shaking his head as he randomly picks something, wondering where in the hell his shirts are all disappearing to. 

After dressing himself, the Warlock magics his makeup in place, puts his necklaces over his head, and slides his rings into place. Before he can leave his bedroom and get to work on some potions he needs to make for a few clients, his phone is pinging with a text. 

**From Jace: SOS. Alec is being MEAN as hell today.**

**From Jace: Magnus please. He just made someone cry.**

**From Jace: By the Angel! What the fuck did that punching bag ever do to him?? [Image Attached]**

Magnus looks at the picture and a smirk slowly flits across his lips. Alec is shirtless and sweaty, his eyes shining omega gold as he takes his frustrations out on a punching bag. His phone pings again and Magnus lets out an amused snort. 

**From Jace: MAGNUS! PLEASE! He’s demanding I spar with him!!**

Magnus puts his phone into his pocket. His hands twist in a circular movement, pushing out and forcing his magic into making a portal. He steps through, finding himself in the New York Institute entrance. Walking through, he nods at passing Shadowhunters. He finds Alec in the training area. 

“Come on, Jace,” Alec says, hopping from one foot to the other. “I’m not letting you off that easy.”

“Easy?” Jace groans, slowly getting back up to his feet. “Just because you’re about to go into heat and need to get all this built up energy out doesn’t mean  _ I  _ should have to get my ass kicked.”

Alec shrugs, taking up a fighting stance. “Is the alpha mad that an omega is kicking his ass?”

“You and I both know being an omega doesn’t make you weaker. Don’t try to use those lines on me, Alec.”

Jace moves forward, swiping at Alec’s legs but Alec is quicker, sidestepping the attempt. They’re both breathing heavily, sweat sliding down their naked torsos. Magnus leans against a beam, silently watching his omega with a proud smile on his face. 

“Damn it,” Jace cries as he’s brought down once more. He lays on his back staring up at the ceiling. “I’m done.”

“Jace,” Alec whines. “Just once more. Come on.”

“No way. Go find your fucking alpha. I can’t take this anymore!”

Alec rolls his eyes, holding out his hand and helping Jace to his feet. “Maybe if you took your training more seriously, I wouldn’t be able to take you down everytime.”

“Let’s try again when you’re not going into heat, Alec,” Jace hisses back. “Or maybe we’ll try again when I’m about to go into rut. Then we’ll see who’s on their back.”

Before the two can continue their bickering, Magnus blows towards Alec, using his magic to carry his scent over to the Shadowhunters. A relieved sigh leaves Jace as Alec’s body goes rimrod straight. Alec’s nostrils flare as his eyes change from their usual hazel to gold. He turns slowly until he’s facing Magnus. 

“Yes. Go,” Jace says, shoving Alec forward. “Go take your alpha to your room and fuck it out. Because no one wants to deal with you until after your heat!”

“Fuck you, Jace,” Alec hisses, stepping towards Magnus. 

“Pretty sure that’s Magnus’ job!”

“That it is,” Magnus says with a smile. Right before Alec is within arm’s reach, Magnus takes a step backwards. Alec takes another step forward only for Magnus to move once more. With that smile across his lips, Magnus turns, taking off in a sprint. 

He hears Alec’s steps sounding against the ground as he chases Magnus. An excited thrill thrums through Magnus’ body as he runs, his omega right on his tail. Sure, it might be more ‘socially acceptable’ for an alpha to chase their omega but once you’ve been alive for centuries, you learn the social norms are sometimes really fun to break. 

Magnus rounds a corner, Alec’s door in sight. Magnus lets out a deep grunt as his front is plastered to the door. Alec pants against his ear as he crowds Magnus against the door. Alec’s hard chest presses against his back, a hand on either side of his head, bracketing him against the door. Magnus tilts his head to the side and Alec’s mouth latches on, nipping and sucking. 

“Fuck. Alexander,” Magnus murmurs, fumbling with the doorknob until it finally clicks open and they both stumble into the bedroom. Alec quickly slams the door shut, stalking towards Magnus. But Magnus is frozen, eyes glued to Alec’s bed. 

“What’s this?” Magnus asks quietly. 

Alec stops, his eyes going wide. His cheeks turn bright red as he looks everywhere but at Magnus. Eventually he shrugs. 

“Alec. These are my clothes.”

“It doesn’t have to be a big deal,” Alec answers, sounding so unsure it makes Magnus’ heart clench. He’s quick to take that uncertainty away. 

“You’re nesting. With my clothes. I want it to be a big deal.”

Alec looks up. “You do?”

“Of course. I know we’ve been sidestepping the big conversation because of all the uncertainties of what’s going on around us. But Alec. What you and I share? It’s very special. I love you.”

“I love you, too,” Alec breathes, his face shining as he steps forward. His hands find Magnus’ hips, pulling him forward until they’re pressed together. “And I want you to be my alpha. Officially.”

Magnus smiles. His hands find Alec’s face. “And I want you to be my omega.”

Their lips come together, both smiling into the kiss. Magnus’ heart beats frantically with elation at hearing those words from Alec. His hands find Alec’s chest, stroking up his bare sides, touching his hard stomach. Fuck, his omega is sexy. 

Magnus groans against Alec’s mouth as he smells the first sign of Alec’s slick. It’s intoxicating and makes him wild with lust. His cock twitches where it’s trapped inside his slacks. Alec’s hands make quick work of sliding his jacket away before moving to unbutton Magnus’ shirt. 

“Need you,” Alec whispers harshly before diving down, burying his face against Magnus throat. One of Magnus’ hands fist the back of Alec’s head, using his hair to direct him. The other he shoves into the front of Alec’s sweatpants, wrapping around Alec’s cock. 

Their movements are frantic and quick, their need wracking higher and higher as their scents thicken, playing off one another’s desires. Magnus can tell the moment Alec’s scent shifts, going from his usual musky smell to something deeper, more tantalizing, drawing out Magnus’ alpha instincts. A rumble goes through his chest. 

“Alpha,” Alec murmurs, stripping Magnus of the rest of his clothes before tossing his sweats aside. Alec crowds Magnus back, shoving him down against his bed before quickly crawling up Magnus’ body. His movements like a wild animal cornering it’s prey and Magnus is ready to be devoured. 

Magnus’ body shudders, watching his omega take exactly what he wants. He scoots back until his head hits the pillows, laying back. He takes in a deep breath, smelling himself all over Alec’s bed and it makes his dick twitch. A moan breaks through his throat as Alec knee walks over Magnus’ torso before turning around and backing up. 

“Please,” Alec moans, sitting back. Who is Magnus to deny his omega anything? His tongue peaks out, licking across Alec’s crack. His taste buds explode with the taste of Alec’s slick and it makes his cock positively  _ ache _ . 

“Fuck, Magnus. Yes,” Alec babbles above him, his head thrown back in pleasure. He moves his hips, riding Magnus’ face as he pleases, too concerned about his own pleasure to care. He’s stunning like this. 

A hand reaches back, gripping Magnus’ hair and pulling his face even further into Alec’s ass. A moan is ripped from his mouth as more slick fills it. Magnus does his best to lick up as much of it as he can before plunging his tongue into Alec’s hole, wiggling it around, drawing random patterns until his omega’s thighs shake. 

“By the Angel! Your mouth is so magical, Magnus. Fuck!”

Magnus brings his hands up to Alec’s ass. One he uses to grip Alec’s hip and the other he uses to finger Alec. He pinpoints his omega’s prostate, rubbing it until Alec is moaning with abandonment, the hand in his hair tightening until his scalp is burning with pin pricks of pain. 

Magnus adds a second finger, scissoring Alec open. Magnus jolts in surprise, his hips coming up off of the bed when Alec wraps a hand around his cock. “Alec!” Magnus gasps out as Alec leans forward and his dick is engulfed in tight, wet heat. “Fuck!”

Alec suckles at the head of his cock, his hand stroking the base. Magnus closes his eyes, reveling in the feel of his omega’s talented mouth before he goes back to Alec’s ass. His tongue plays circles around his fingers and Alec grinds back, riding his ass against Magnus’ mouth. 

“Fuck. I’m ready. I’m so ready,” Alec murmurs, sliding forward. With a knee on each side of Magnus’ hips, Alec takes Magnus’ cock in hand, holding it steady before slowly sliding down. Magnus watches, his mouth open in wonder, his eyes never leaving Alec’s hole as it swallows his dick, stretching around the intrusion. 

“Alexander,” Magnus gasps out, his hands finding Alec’s hips. The long, sleek line of Alec’s back glistens with sweat as he seats himself in Magnus’ lap. The dark runes a stark contrast to Alec’s creamy skin. He swivels his hips, clenching around Magnus’ dick, forcing a groan of pleasure from his mouth. 

“Fuck, Alec. You look so beautiful like this.” Alec begins to move. His hips rise up until only Magnus’ head is still inside of him before falling back down. Magnus can’t look away, watching as Alec’ ass slides up and down his cock. He’s so fucking hot, and tight, and  _ wet _ around his dick, and it has Magnus closing his eyes, moaning at the feeling. 

Alec’s hips continue to move in a sensual dance as he chases his pleasure. Magnus knows what he needs, his omega needs his knot. 

“Turn over, my beautiful omega. Need to see you,” Magnus says, his fingers digging into Alec’s hips for another moment before he lets go. Alec sits forward until Magnus’ dick is slipping free before Alec is turning around to face him. 

Alec leans down, taking Magnus’ lips in a searing kiss. His tongue plunges into Magnus’ mouth as his hips continue to move, grinding his ass crack against Magnus’ cock, slicking sliding everywhere. Fuck, it’s maddening how turned on Magnus is. 

Magnus slides a hand down, holding his dick up. “Take what you need, Alexander.”

And he does. Alec rolls his hips, taking all of Magnus in one go. Alec’s head tilts up as he lets out a wanton moan. He’s so uncaring when he’s in heat, unashamed of what he wants, what he needs. 

“Yes. Come on, baby. Do you want my knot?”

Alec’s hand brace against his chest as he rides Magnus. “Yes. Want it, Magnus. Give it to me.”

Magnus plants his feet on the bed before thrusting up into Alec’s tight heat. Alec falls against his chest, burying his nose against Magnus’ throat as he shoves up into Alec. Magnus’ arms come around Alec’s back, holding him against his chest. When Alec begins sucking against Magnus’ pulse point, Magnus moans, feeling his knot slowly forming, widening Alec’s entrance on every thrust. 

“Fuck. Need it, Magnus,” Alec babbles against Magnus’ throat. “Knot me, Alpha. Mate me, Magnus. Please!”

Alec’s cries spur Magnus on. He thrusts up hard over and over until his knot finally catches, expanding inside of his omega until they’re tied together. He grinds his hips up, no doubt rubbing his knot against Alec’s prostate until his omega is clenching down and shouting, his cock spurting his seed between their bellies. 

Alec’s teeth dig into his neck. The jolt of pain startles Magnus’ orgasm right out of him and he fills his omega with his cum. Pain quickly morphs into bone numbing pleasure that leaves Magnus borderline delirious. Alec grabs him by the hair once more, bringing Magnus’ mouth to his neck. He bites down, groaning when Alec’s warm blood hits his tongue. As soon as he pulls back, he feels their bond click into place. It’s like Magnus heart is fractured, completely pulled apart and then put back together, now with a piece of Alec sliding into place along with the rest. 

Magnus’ head falls back, his breathing slowly coming back down to normal as he closes his eyes. He can  _ feel _ Alec and their connection inside his chest and a choked sob leaves his throat. His arms tighten around his omega. 

“Thank you,” he whispers into Alec’s hair. 

Alec finally raises his head from where it was buried in Magnus’ throat. There’s a smile so wide across his face it makes his cheeks dimple. Alec’s eyes are bright, full of life. “I love you,” he breathes before kissing Magnus’ lips softly. “I love you so much, Magnus. You don’t have to thank me for making  _ my _ dreams come true.”

Magnus pulls Alec down, pressing kiss after kiss against his face. Alec lets out a laugh, pushing Magnus’ face away. “So,” he asks, gently touching Magnus’ face. “How did you know I needed you?”

Magnus smirks. “An alpha always know.”

Alec nods. “Mhmm. Right. So Jace texted you then?”

“Jace texted me.”

Alec snorts but looks fond as he whispers, “it’s about time my parabatai did something useful today.” Then he snuggles into Magnus’ chest with a yawn. Right before Magnus falls asleep, a rumble radiates from his chest. But it’s not coming from Magnus. No, it’s Alec. A content purr sounding through the room as he sleeps. This might be the first time Magnus has heard his omega purr but he promises himself it won’t be the last. Magnus will do anything to keep his omega this content and happy for their very, very long life together. 

Magnus’ phone pings. With a wave of his hand, he conjures his phone, snort at the message he finds. 

**From Jace: You’re welcome assholes.**


End file.
